I have been reading "An Introduction To Systems Biology - Design Principles of Biological Circuits" by Uri Alon, over the past while and I am finding it fascinating. My first reaction was seeing how much DNA is like code, only so much more. DNA and all the surrounding mechanisms, are like code which writes code which writes code, that then finally executes to do something useful. This produces a system with a high degree of flexibility that is capable of dealing with the many variations of life. The other realization is that life is not random, or at least not completely, that life is the way it is for a reason. This does not mean that, if we were to start all over again that everything would happen the same, but that common motifs and themes would arise, similar to what we see today.
Everything around us is there because it works and does something useful. It may not always be optimal and free of negative consequences, but when you consider the sum total of everything, it come out positive. If it did not work, then the behavior would be changed by random mutations, that could happen at anytime.